You Control the App; You Control the Hardware

Some interesting gadgets are coming to market--hardware that you control with apps designed for your iPhone, iPad and (on occasion) Android device.

Dubbed "appcessories," some of these devices are amazingly innovative or fun. Others, though creative, are so offbeat that you have to wonder whether people will actually use them.

Check out PCWorld's latest selection of the best new appccessories, with a few oddballs thrown in for fun.

gTar by Incident: It's Cool

This faux guitar, designed to help users learn how to play a real guitar, isn't a toy; it feels almost as substantial as a real electric guitar. After you dock an iPhone in the gTar's body and load its app onto your phone, a series of LEDs will light up on its neck. The teaching app shows you which strings to play and offers three levels of difficulty. As you improve, you receive less assistance.

As your proficiency increases, gTar offers you less help. Once you can play on your own, you can use Free Play mode to turn the guitar into various other instruments, such as a synthesizer.

Availability: Incident expects this item to retail for $450 at Incidentgtar.com.

Fitbit Aria Wi-Fi Smart Scale: It's Cool

If you're keen on losing weight or getting fit, the Fitbit Smart Scale is for you. Much like the Withings Wi-Fi Scale, the Fitbit Smart Scale lets you sync data on your weight and other body measurements to the cloud. However, Fitbit's online platform is more robust. For a premium, you can even see how your body metrics stack up against others in the Fitbit community.

The scale itself uses electrodes in its glass surface to send an very slight electric signal through your body to determine how much fat and/or lean mass you're carrying around. The Fitbit apps for iOS and Android let you receive all of this motivational information on your phone or tablet whenever you need it.

Orbotix Sphero: It's Cool

The Sphero is a 5.9-ounce robot ball that rolls about on the floor as it follows directions from your phone or tablet that it receives via Bluetooth.

The Sphero can reach a speed of 3 feet per second (roughly 2 miles per hour), and it uses an internal guidance system that includes a gyro, an accelerometer, and compasses. Its multicolored LEDs enable you to use it in the dark or to designate team colors for sides while playing games.

You can use a number of apps with your Sphero, including one that lets you race it or play golf in an entirely new way.

PhysicalApps TheO: It's Weird

The TheO combines a bowling-ball-size foam ball with apps that utilize your smartphone's accelerometer. You download TheO apps to your iOS or Android phone, and stick the phone in the center of the foam ball--and you're ready to play games like Hot Potato, where the goal is to not get caught holding the ball when the potato explodes on the screen.

The app figures out when the ball is tossed from person to person.

Availability: The TheO was demoed at Toy Fair 2012 in New York a few months ago. Check PhysicalApps.com if you like the idea of bouncing, tossing, or rolling your smartphone around for fun.

Escort SmartRadar: It's Innovative

The detector then integrates with Escort's Live ticket-protection app, which lets you share the hits other users are getting on their detectors and updates them in real time on your phone's display. Radar dodging: Engaged!

Philips In.Sight Wireless Home Monitor: It's Cool

Simply download the free In.Sight app to your iPhone or iPad, pair it with the In.Sight monitor hardware (using a QR code, if you like), place the monitor somewhere within range of your Wi-Fi network, and voilà--you're set up for remote monitoring of anything you like from anyplace where you can obtain an Internet connection on your phone or tablet.

The monitor will notify you whenever it detects motion or noise; if you want to record what the monitor sees, you can set up your system to upload video to a private YouTube channel.

MOTRR Galileo: It's Innovative

Couple Motrr's Galileo base with its companion app, and you can control a phone or tablet sitting on the base by swiping your finger on another iOS phone or tablet that has the app installed. This combination could be useful to photographers, cinematographers, people conducting video chats, and parents who want to keep tabs on squirrely kids.

With infinite 360-degree pan-and-tilt at speeds of up to 200 degrees per second in any orientation, Galileo is extremely popular on fund-raising site Kickstarter: Motrr originally set a goal of raising $100,000 in funding, but it has garnered more than $700,000 so far.

Ion Audio Piano Apprentice: It's Cool

For what you might pay a live teacher for a handful of lessons, you can buy Ion Audio Piano Apprentice for iPad, iPod, and iPhone, and learn to play piano whenever it's convenient for you.

The Piano Apprentice is a 25-note keyboard with built-in speakers. Download the free Piano Apprentice app and install your Apple mobile device on the Apprentice, and the screen will show you a professional piano teacher's hands placed on the keys where yours should be.

If that's not clear enough for you, the correct keys for whatever you're supposed to play light up as well. This appcessory makes for an inexpensive piano teaching tool, especially when coupled with the iPad's large screen.

Scosche RDTX Portable Radiation Detector: It's Weird

The RDTX Portable Radiation Detector plugs into your iPhone or iPod Touch via the dock connector, and lets you detect radiation levels around you. You can also share geotagged results on Facebook, Twitter, and Google Maps via the RadTest app.

Why do we label this item "weird"? Let's just say that we don't plan to stockpile post-Apocalyptic survival gear until the Apocalypse is a little farther advanced.

PoP Video iPhone Projector: It's Innovative

The low resolution and poor light output of most pico projectors tends to make them less useful in practice than in theory.

But the PoP Video projector can output at qHD resolution--for a 960-by-540-pixel image--after you attach it to your iPhone’s 30-pin connection. And the PoP Video iOS app lets you do such things as project and control services (like photo albums) from your iPhone, and establish custom projection settings for your images.

Another plus: The projector uses its own internal battery, which should support up to 2 hours of video playback.

Jumpsport.com iBounce Trampoline for Kids: It's Weird

A trampoline as an iPad accessory? This trampoline has a mount that securely holds your iPad, Kindle, Nook, or other tablet in place (you hope!) so that your child can view JumpSport content or other podcasts, videos, or eBooks while merrily bouncing along.

Availability:Jumpsport.com | $130 for a bundle that includes the trampoline, tablet holder, and DVD.